We have a floating laminate floor installed over concrete and would like solid hardwood flooring instead. Can we install hardwood planks over the existing laminate floor or do we have to pull that out and put in a sub-floor?

The laminate must go.

An engineered board is recommended, when installing over concrete. Either floating or direct gluedown.

It's also very easy to remove once you get started. If you really desire a 3/4" solid hardwood, options are limited with concrete slabs(see link below)--although some newcomers to the business will say it's no problem to glue it down. Experienced professionals will always stear clear.

http://www.hardwoodinstaller.com/hardwo ... ncrete.htm